Method for making a catalyst comprising a phosphorus modified zeolite to be used in a mto process

ABSTRACT

The present invention is the use of a catalyst in a MTO process to convert an alcohol or an ether into light olefins wherein said catalyst comprises a phosphorus modified zeolite and is made by a method comprising the following steps in this order,
     a) the essential portion of the phosphorus is introduced into a zeolite comprising at least one ten members ring in the structure,   b) the phosphorus modified zeolite of step a) is mixed with at least a component selected among one or more binders, salts of alkali-earth metals, salts of rare-earth metals, clays and shaping additives,   b)* making a catalyst body from mixture b),   c) an optional drying step or an optional drying step followed by a washing step,   d) a calcination step,   d*) an optional washing step followed by drying,   e) optionally a small portion of phosphorus is introduced in the course of step b) or b)* or at end of step b) or b)*.

FIELD OF THE INVENTION

The present invention relates to a method for making a catalystcomprising a phosphorus modified zeolite to be used in a MTO process.More precisely it relates to the use of a catalyst in a MTO process toconvert an alcohol or an ether into light olefins wherein said catalystcomprises a phosphorus modified zeolite. Olefins are traditionallyproduced from petroleum feedstocks by catalytic or steam crackingprocesses. These cracking processes, especially steam cracking, producelight olefin(s), such as ethylene and/or propylene, from a variety ofhydrocarbon feedstock. Ethylene and propylene are important commoditypetrochemicals useful in a variety of processes for making plastics andother chemical compounds.

The limited supply and increasing cost of crude oil has prompted thesearch for alternative processes for producing hydrocarbon products. TheMTO process produces light olefins such as ethylene and propylene aswell as heavy hydrocarbons such as butenes. Said MTO process is theconversion of methanol or dimethylether by contact with a molecularsieve. The interest in the methanol to olefin (MTO) process is based onthe fact that methanol can be obtained from coal or natural gas by theproduction of synthesis gas which is then processed to produce methanol.

BACKGROUND OF THE INVENTION

Catalysts comprising a phosphorus modified zeolite (the phosphorusmodified zeolite is also referred as P-zeolite) are known The followingprior arts have described various methods to make said catalysts.

US 2006 106270 relates to the use of a dual-function catalyst system inthe hydrocarbon synthesis reaction zone of an oxygenate to propylene(OTP) process that operates at relatively high temperatures preferablywith a steam diluent and uses moving bed reactor technology. Thedual-functional catalyst system comprises a molecular sieve havingdual-function capability dispersed in a phosphorus-modified aluminamatrix containing labile phosphorus and/or aluminum anions. It isexplained that the hydrothermal stabilization effect that is observedwhen this phosphorus-modified alumima matrix is utilized is caused bymigration or dispersion of phosphorus and/or aluminum anions from thismatrix into the bound molecular sieve. These anions are then availableto repair, anneal and/or stabilize the framework of the molecular sieveagainst the well-known dealumination mechanism of molecular sieveframework destruction or modification that is induced by exposure tosteam at temperatures corresponding to those used in the OTP reactionzone and in the regeneration zone.

U.S. Pat. No. 4,356,338 discloses a method for decreasing catalystcoking and extending the usable catalyst life by pre-treatment of thecatalyst with steam and/or a phosphorus-containing compound.Pretreatment may be accomplished by the impregnation of the catalyst orof the catalyst/binder combination with a phosphorus containing compoundto deposit approximately 4 wt % of phosphorus thereon, and preferablyfrom about 2% to about 15% by weight of phosphorus, based on the weightof the catalyst or catalyst/binder matrix being treated.

U.S. Pat. No. 5,231,064 is directed to a fluid catalyst comprising clayand a zeolite, at least one of which has been treated with a phosphoruscontaining compound, for example ammonium dihydrogen phosphate orphosphoric acid, and which is spray dried at a low pH, preferably lowerthan about 3. Said catalysts are deemed to advantageously exhibitreduced attrition.

EP 511013 A2 provides an improved process for the production of C2-C5olefins from higher olefinic or paraffinic or mixed olefin and paraffinfeedstocks. In accordance with this prior art, the hydrocarbon feedmaterials are contacted with a particular ZSM-5 catalyst at elevatedtemperatures, high space velocity and low hydrocarbon partial pressureto produce lower olefins. The catalysts is treated with steam prior touse in the hydrocarbon conversion. The active catalyst component isphosphorus-containing ZSM-5 having a surface Si/Al ratio in the range20-60. Preferably, the phosphorus is added to the formed ZSM-5 as byimpregnating the ZSM-5 with a phosphorus compound in accordance with theprocedures described, for example, in U.S. Pat. No. 3,972,832. Lesspreferably, the phosphorus compound can be added to the multicomponentmixture from which the catalyst is formed. The phosphorus compound isadded in amount sufficient to provide a final ZSM-5 composition having0.1-10 wt. % phosphorus, preferably 1-3 wt. %.

The phosphorus-containing ZSM-5 is preferably combined with knownbinders or matrices such as silica, kaolin, calcium bentonite, alumina,silica aluminate and the like. The ZSM-5 generally comprises 1-50 wt. %of the catalyst composition, preferably 5-30 wt. % and most preferably10-25 wt. %.

EP 568913 A2 describes a method for preparing a ZSM-5 based catalystadapted to be used in the catalytic conversion of methanol or dimethylether to light olefins, wherein it comprises the following consecutivesteps:

-   -   mixing a zeolite ZSM-5 based catalyst with silica sol and        ammonium nitrate solution,    -   kneading, moulding, drying and calcining the mixture,    -   exchanging the modified zeolite with a solution of HCl at 70-90°        C.,    -   drying and calcining the H-modified zeolite,    -   impregnating the H-modified zeolite with phosphoric acid under        reduced pressure,    -   drying and calcining the P-modified zeolite,    -   impregnating the P-modified zeolite with a solution of rare        earth elements under reduced pressure,    -   drying and calcining the P-rare earths-modified zeolite,    -   hydrothermally treating the P-rare earths-modified zeolite at        500-600° C. with water vapour, and    -   calcining the modified zeolite.

WO 03 020667 relates to a process of making olefin, particularlyethylene and propylene, from an oxygenate feed, comprising contacting anoxygenate feed with at least two different zeolite catalysts to form anolefin composition, wherein a first of the zeolite catalysts contains aZSM-5 molecular sieve and a second of the zeolite catalysts contains azeolite molecular sieve selected from the group consisting of ZSM-22,ZSM-23, ZSM-35, ZSM-48, and mixtures thereof. The ZSM-5 can beunmodified, phosphorous modified, steam modified having a microporevolume reduced to not less than 50% of that of the unsteamed ZSM-5, orvarious mixtures thereof. According to one embodiment, the zeolite ismodified with a phosphorous containing compound to control reduction inpore volume. Alternatively, the zeolite is steamed, and the phosphorouscompound is added prior to or after steaming. The amount of phosphorous,as measured on an elemental basis, is from 0.05 wt. % to 20 wt. %, andpreferably is from 1 wt. % to 10 wt. %, based on the weight of thezeolite molecular sieve. Preferably, the atomic ratio of phosphorus toframework aluminum (i.e. in the zeolite framework) is not greater than4:1 and more preferably from 2:1 to 4:1. Incorporation of a phosphorusmodifier into the catalyst of the invention is accomplished, accordingto one embodiment, by contacting the zeolite molecular sieve eitheralone or the zeolite in combination with a binder with a solution of anappropriate phosphorus compound. The solid zeolite or zeolite catalystis separated from the phosphorous solution, dried and calcined. In somecases, the added phosphorous is converted to its oxide form under suchconditions. Contact with the phosphorus-containing compound is generallyconducted at a temperature from 25° C. to 125° C. for a time from 15minutes to 20 hours. The concentration of the phosphorus in the zeolitemay be from 0.01 wt. % to 30 wt. %. This prior art discloses anon-formulated P-ZSM-5.

A common way to produce a formulated P-zeolite containing catalystconsists in the impregnation of the already pre-formulated zeolite (e.g.the zeolite+a binder) with P-compounds or phosphorous addition to thereaction medium.

A great number of patents disclose the recipe for preparation of theactive phase (non-formulated phosphated zeolite) by means of zeolitephosphatation and their use in methanol conversion. Some of thesereferences contain the options of further blending the active phase withbinder. However, the active phase is good as such in the reaction. It isassumed that the binder plays only the role of diluent what is notnormally the case. The process of the present invention differs from agreat number of known in the art preparation of the P-zeolite basedactive phase due to referring to preparation of formulated catalyst andimplementation of the phosphatation step at the first stage. Moreoverthe phosphatation of the zeolite (formation of the active phase) at thefirst step does not necessarily leads to a suitable catalyst. On thecontrary, the overall recipe results in a good catalyst.

The catalyst referred to in the present invention comprises a zeoliteand at least a component selected among one or more binders, salts ofalkali-earth metals, salts of rare-earth metals, clays and shapingadditives. The metal salts, binder and clays may also adsorb thephosphorous interfering and even competing with zeolite preventing aproper zeolite phosphatation. The presence of traces of metals adsorbingpreferentially phosphorous could even more perturb the zeolitephosphatation. This often leads to non-selective catalysts due to poorreproducibility and binder pore plugging. The method of the presentinvention provides a solution to selectively phosphatize zeoliteovercoming the side effects of binder, metal salts or clays presence.Thus, the invention discloses that the preparation of the catalystrequires the phosphatation of zeolite before introducing any othercomponents such as binder, metals, clays and shaping additives. Thismethod insures the reproducibility of the preparation, the hydrothermalstability and the good catalyst performance.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to the use of a catalyst in a MTO processto convert an alcohol or an ether into light olefins wherein saidcatalyst comprises a phosphorus modified zeolite and is made by a methodcomprising the following steps in this order,

a) the essential portion of the phosphorus is introduced into a zeolitecomprising at least one ten members ring in the structure,b) the phosphorus modified zeolite of step a) is mixed with at least acomponent selected among one or more binders, salts of alkali-earthmetals, salts of rare-earth metals, clays and shaping additives,b)* making a catalyst body from mixture b),c) an optional drying step or an optional drying step followed by awashing step,d) a calcination step,d*) an optional washing step followed by drying,e) optionally a small portion of phosphorus is introduced in the courseof step b) or b)* or at end of step b) or b)*.

Advantageously the zeolite (or molecular sieve) contains less that 1000wppm of sodium, less that 1000 wppm of potassium and less that 1000 wppmof iron.

Advantageously the zeolite contains less than 200 ppm of alkali andalkali-earth metals.

Advantageously the bulk Si/Al ratio of initial zeolite is below 20.Advantageously the zeolite contains less than 100 ppm of red-ox andnoble elements such as Zn, Cr, Ti, Rh, Mn, Ni, V, Mo, Co, Cu, Cd, Pt,Pd, Ir, Ru, Re.

The phosphorus source is advantageously substantially free of metalcompounds. It is advantageously selected among H3PO4, ammoniumphosphates or organic P-compounds.

In an embodiment the phosphorus of step e) can be introduced as acomponent of the binder or of the clays.

The amount of phosphorous introduced into the zeolite at step a) can befrom 0.5 to 30 wt %, but preferably from 0.5 to 9%.

Advantageously the molar P/Al ratio at step a) is higher than 1 byproviding the excess of phosphatation agent.

The formulation steps b) and c) can be performed by means ofspray-drying, extrusion, oil drop etc.

In accordance with the present invention, at the step c) and d*) thecatalyst is treated with water for a period of time advantageously from0.5 to 48 hours, preferably for a period of time from about 1 to 36hours and most preferably from about 2 to 24 hours. The water is at atemperature between about 10° and 180° C., preferably between about 15°and 100° C. and most preferably between about 20° and 60° C. Followingthe water treatment, the catalyst is dried at about 60-350° C.Optionally, the water can contain ammonium or/and at least one of theions selected from the group consisting of Li, Ag, Mg, Ca, Sr, Ba, Ce,Al, La, and mixtures thereof.

At end of step a) it is not mandatory to separate the P-zeolite from thereaction medium, the binders, salts of alkali-earth metals, salts ofrare-earth metals, clays and shaping additives can be added directlyinto the reaction medium.

In a preferred embodiment, a low sodium content binder and clays areused.

Before the phosphatation of step a) the zeolite can be subjected tovarious treatments including, ion exchange, steaming, acid treatment,surface passivating by silica deposition etc.

In a preferred embodiment the sodium content in the binder and the claysis less that 5000 ppm of sodium.

Preferred zeolite structures are selected from the MFI, MTT, FER, MEL,TON, MWW, EUO, MFS, ZSM-48.

DETAILED DESCRIPTION OF THE INVENTION

As regards the MTO process to convert an alcohol or an ether into lightolefins, this process has been described in many patent applications.One can cite WO 20041016572, WO 2005/016856, WO 2008/110526, WO2008/110528, WO 2008/110530, WO 2009/016153, WO 2009/156434 and WO2009/016154, the content of which is incorporated in the presentapplication.

As regards the zeolite containing at least one 10 members ring into thestructure, one can cite the crystalline silicates. It is by way ofexample of the MFI (ZSM-5, silicalite-1, boralite C, TS-1), MEL (ZSM-11,silicalite-2, boralite D, TS-2, SSZ-46), FER (Ferrierite, FU-9, ZSM-35),MTT (ZSM-23), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), TON (ZSM-22, Theta-1,NU-10), EUO (ZSM-50, EU-1), MFS (ZSM-57) and ZSM-48 family ofmicroporous materials consisting of silicon, aluminium, oxygen andoptionally boron.

The three-letter designations “MFI” and “MEL” each representing aparticular crystalline silicate structure type as established by theStructure Commission of the International Zeolite Association. Examplesof a crystalline silicate of the MFI type are the synthetic zeoliteZSM-5 and silicalite and other MFI type crystalline silicates known inthe art. Examples of a crystalline silicate of the MEL family are thezeolite ZSM-11 and other MEL type crystalline silicates known in theart. Other examples are Boralite D and silicalite-2 as described by theInternational Zeolite Association (Atlas of zeolite structure types,1987, Butterworths). The preferred crystalline silicates have pores orchannels defined by ten oxygen rings.

Crystalline silicates are microporous crystalline inorganic polymersbased on a framework of XO₄ tetrahedra linked to each other by sharingof oxygen ions,

where X may be trivalent (e.g. Al, B, . . . ) or tetravalent (e.g. Ge,Si, . . . ). The crystal structure of a crystalline silicate is definedby the specific order in which a network of tetrahedral units are linkedtogether. The size of the crystalline silicate pore openings isdetermined by the number of tetrahedral units, or, alternatively, oxygenatoms, required to form the pores and the nature of the cations that arepresent in the pores. They possess a unique combination of the followingproperties: high internal surface area; uniform pores with one or morediscrete sizes; ion exchangeability; good thermal stability; and abilityto adsorb organic compounds. Since the pores of these crystallinesilicates are similar in size to many organic molecules of practicalinterest, they control the ingress and egress of reactants and products,resulting in particular selectivity in catalytic reactions. Crystallinesilicates with the MFI structure possess a bidirectional intersectingpore system with the following pore diameters: a straight channel along[010]: 0.53-0.56 nm and a sinusoidal channel along [100]: 0.51-0.55 nm.Crystalline silicates with the MEL structure possess a bidirectionalintersecting straight pore system with straight channels along [100]having pore diameters of 0.53-0.54 nm.

In a specific embodiment the crystalline silicate is steamed to removealuminium from the crystalline silicate framework before phosphatation.The steam treatment is conducted at elevated temperature, preferably inthe range of from 425 to 870° C., more preferably in the range of from540 to 815° C. and at pressure 1-5 bara and at a water partial pressureof from 13 to 200 kPa. Preferably, the steam treatment is conducted inan atmosphere comprising from 5 to 100% steam. The steam atmospherepreferably contains from 5 to 100 vol % steam with from 0 to 95 vol % ofan inert gas, preferably nitrogen. A more preferred atmosphere comprises72 vol % steam and 28 vol % nitrogen i.e. 72 kPa steam at a pressure ofone atmosphere. The steam treatment is preferably carried out for aperiod of from 1 to 200 hours, more preferably from 20 hours to 100hours. As stated above, the steam treatment tends to reduce the amountof tetrahedral aluminium in the crystalline silicate framework, byforming alumina.

Additionally, if during the preparation of the zeolite to bephosphatized alkaline or alkaline earth metals have been used, themolecular sieve might be subjected to an ion-exchange step.Conventionally, ion-exchange is done in aqueous solutions using ammoniumsalts or inorganic acids.

As regards the introduction of P into the zeolite, by way of examplesaid P-modified zeolite is made by a process comprising in that order:

introducing P;

separation of the solid from the liquid if any;

an optional washing step or an optional drying step or an optionaldrying step followed by a washing step;

a calcination step;

Optionally, the contact with the phosphorus-containing compound isconducted at a temperature from 40° C. to 110°. P can be introduced byany means or, by way of example, according to the recipe described inU.S. Pat. No. 3,911,041.

The separation of the liquid from the solid is advantageously made byfiltering at a temperature between 0-90° C., centrifugation at atemperature between 0-90° C., evaporation or equivalent.

Optionally, the zeolite can be dried after separation before washing.Advantageously said drying is made at a temperature between 40-600° C.,advantageously for 1-10 h. This drying can be processed either in astatic condition or in a gas flow. Air, nitrogen or any inert gases canbe used.

The washing step can be performed either during the filtering(separation step) with a portion of cold (<40° C.) or hot water (>40 but<90° C.) or the solid can be subjected to a water solution (1 kg ofsolid/4 liters water solution) and treated under reflux conditions for0.5-10 h followed by evaporation or filtering.

According to a specific embodiment the phosphorous modified zeolite ismade by a process comprising in that order:

selecting a zeolite;

steaming at a temperature ranging from 400 to 870° C. for 0.01-200 h;

optional leaching with an aqueous acid solution at conditions effectiveto remove a substantial part of Al from the zeolite;

introducing P with an aqueous solution containing the source of P atconditions effective to introduce advantageously at least 0.05 wt % ofP;

separation of the solid from the liquid;

an optional washing step or an optional drying step or an optionaldrying step followed by a washing step;

an optional calcination step.

In the steam treatment step, the temperature is preferably from 420 to870° C., more preferably from 480 to 760° C. The pressure is preferablyatmospheric pressure and the water partial pressure may range from 13 to100 kPa. The steam atmosphere preferably contains from 5 to 100 vol %steam with from 0 to 95 vol % of an inert gas, preferably nitrogen. Thesteam treatment is preferably carried out for a period of from 0.01 to200 hours, advantageously from 0.05 to 200 hours, more preferably from0.05 to 50 hours. The steam treatment tends to reduce the amount oftetrahedral aluminium in the crystalline silicate framework by formingalumina.

The leaching can be made with an organic acid such as citric acid,formic acid, oxalic acid, tartaric acid, malonic acid, succinic acid,glutaric acid, adipic acid, maleic acid, phthalic acid, isophthalicacid, fumaric acid, nitrilotriacetic acid,hydroxyethylenediaminetriacetic acid, ethylenediaminetetracetic acid,trichloroacetic acid trifluoroacetic acid or a salt of such an acid(e.g. the sodium salt) or a mixture of two or more of such acids orsalts. The other inorganic acids may comprise an inorganic acid such asnitric acid, hydrochloric acid, methansulfuric acid, phosphoric acid,phosphonic acid, sulfuric acid or a salt of such an acid (e.g. thesodium or ammonium salts) or a mixture of two or more of such acids orsalts.

The residual P-content is adjusted by P-concentration in the aqueousacid solution containing the source of P, drying conditions and awashing procedure if any. A drying step can be envisaged betweenfiltering and washing steps.

As regards step b), and the binder, it is selected so as to be resistantto the temperature and other conditions employed in the processes usingthe catalyst. The binder is an inorganic material selected from silica,metal silicates, metal oxides such as Zr0₂ and/or metals, or gelsincluding mixtures of silica and metal oxides. It is desirable toprovide a catalyst having a good crush strength. This is because incommercial use, it is desirable to prevent the catalyst from breakingdown into powder-like materials. Such oxide binders have been employednormally only for the purpose of improving the crush strength of thecatalyst. A particularly preferred binder for the catalyst of thepresent invention comprises silica. The relative proportions of thefinely divided crystalline silicate material and the inorganic oxidematrix of the binder can vary widely.

As regards step b)*, in addition to enhancing the catalyst strengthproperties, the matrix material allows the molecular sieve crystallitepowder to be bound into larger particle sizes suitable for commercialcatalytic processes. The formulation of the mixture b) may be formedinto a wide variety of shapes including extrudates, spheres, pills, andthe like. The binder material is often, to some extent, porous in natureand may or may not be effective to promote the desired conversion ofmethanol to light olefins. The matrix material may also promoteconversion of the feed stream and often provides reduced selectivity tothe desired product or products relative to the catalyst.

Types of silica sols used to form a bound catalyst for use in the MTOprocess are commercially available as aquasols or organosols containingdispersed colloidal silica particles. For example, sodium silicate canbe used as a silica sol. Otherwise, a silica gel, fumed or pyrogenicsilica may also be used to provide a silica binder in the molecularsieve catalyst. Silicic acid is another possible source of silica. If amagnesia binder is desired, the starting slurry will contain hydrolyzedmagnesium alkoxide. When a zirconia binder is used for the catalystpreparation, the preferred starting acidic sol is an aqueous zirconiumacetate solution, which is preferably combined with a urea gellingagent.

As regards to the clays, It is preferred to optionally add a clay to thecatalyst. The clay is usually added to the catalyst slurry before themixing of the molecular sieve and binder, and the resultant slurry ismixed and spray dried. Clays that are used in this process to form ahardened product include, but are not limited to, kaolin, kaolinite,montmorillonite, saponite, bentonite, attapulgite and halloysite. Clayscontribute to strength as a binder enhancing the attrition resistanceproperties of the catalyst particles, and clays in combination withbinders contribute to the hardness of the particles. Clays also start assmall particles and have a higher density, such that when combined withthe molecular sieve and binder provide for denser particles, impartingthe desirable characteristic of higher density.

As regards the salts of alkali-earth metals, salts of rare-earth metals,the metals are advantageously Ca, Mg, Sr, Ce, La or a combinationthereof.

As regards the proportions of the P-zeolite, the one or more binders,salts of alkali-earth metals, salts of rare-earth metals, clays andshaping additives, advantageously the proportion of the P-zeolite isfrom 5 to 95 w % of the catalyst. The catalyst comprises the P-zeoliteand at least a component selected among one or more binders, salts ofalkali-earth metals, salts of rare-earth metals, clays and shapingadditives. The amount of P-modified zeolite which is contained in thecatalyst ranges more advantageously from 15 to 90 weight percent of thetotal catalyst, preferably 20 to 70 weight percent of the catalyst. Whenadding clay, the clay forms between about 10 and about 80 wt-% of thedried catalyst product. The concentration of the salts of alkali-earthmetals and salts of rare-earth metals can be from 0.1 to 15 wt % of thecatalyst on metal basis (Me). Advantageously the molar ratio of(Al+Me)/P in the catalyst is in the range 0.5 to 3, where the Me isalkali or rare-earth.

In mixing the P-zeolite with at least a component selected among one ormore binders, salts of alkali-earth metals, salts of rare-earth metalsand clays, the catalyst may be formulated into pellets, extruded intoother shapes, or formed into spheres or a spray-dried powder. Typically,all the ingredients are mixed together by a mixing process. By way ofexample in such a process, the binder, for example silica, in the formof a gel is mixed with the P-zeolite and the resultant mixture isextruded into the desired shape, for example cylindic or multi-lobebars. Spherical shapes can be made in rotating granulators or byoil-drop technique. Small spheres can further be made by spray-drying acatalyst suspension.

Thereafter, the catalyst is calcined in air or an inert gas, typicallyat a temperature of from 350 to 900° C. for a period of from 1 to 48hours. Optionally the air or an inert gas may contain steam inconcentration from 10 to 90 vol %.

As regards steps c) and d*), the dried or calcined, shaped catalystparticles may optionally be finished by contacting them with water or anaqueous exchange solution of an ionic compound. The aqueous exchangesolution is characterized in that it is effective for removing undesiredmetallic cations that may occupy the ion exchange sites of the molecularsieve or/and introduction a desirable metallic cations. The undesirablemetallic cations are Na, K, Fe, Zn, Cr, Mn, Ni, V, Mo, Co, Cu, Cd. Thesespecies can originate from inorganic template material present in themolecular sieve or, more commonly, stem from the inorganic oxide bindersource material (e.g. aluminum sol). In the processing service for whichthe catalyst is designed (e.g. the conversion of methanol to olefins)these metal cations can promote side reactions, slow the desiredreaction rate, or otherwise complicate the catalysis of the desiredreaction. Some sources of the inorganic oxide binder are essentiallyfree of undesired metal cations and therefore the dried particlesproduced using such sources would not necessarily require contact withan exchange solution. Water washing both before and after the finishingstep may be desired to flush the catalyst of undesired solids and/orresidual exchange solution.

In accordance with the present invention, at the step c) and d*) thecatalyst is treated with water for a period of time advantageously from0.5 to 48 hours, preferably for a period of time from about 1 to 36hours and most preferably from about 2 to 24 hours. The water was at atemperature between about 10° and 180° C., preferably between about 15°and 100° C. and most preferably between about 20° and 60° C. Followingthe water treatment, the catalyst was dried at about 60-350° C.Optionally, the water can contain ammonium or at least one of themetallic cations ions selected from the group consisting of Li, Ag, Mg,Ca, Sr, Ba, Ce, Al, La, and mixtures thereof which do not promote sidereactions and stabilize the zeolite against steam dealumination.

EXAMPLES Example 1

A sample of zeolite ZSM-5 (Si/Al=12) in H-form (contained 445 ppm of Na,below 25 ppm of K, 178 ppm of Fe, 17 ppm of Ca & synthesized withouttemplate) was steamed 550° C. for 6 h in 100% H₂O at atmosphericpressure. The sample is hereinafter identified as sample A.

Steamed solid A was subjected to a contact with 3.14M solution of H₃PO₄for 4 h under reflux condition (4.2 ml/1 g pf zeolite). Then the solidwas separated from the liquid phase at room temperature by filteringfrom the solution. Obtained material was dried at 200° C. for 16 h. Thesample is hereinafter identified as sample B.

100 g of steamed solid A was subjected to a contact with 31 g of 85 wt %H3PO4 in 400 ml H2O under reflux condition for 4 h. Then the solutionwas cooled down and 10 g of xonotlite (calcium silicate) were added tothe mixture followed by stirring at room temperature for 30 min andevaporation. The sample is hereinafter identified as sample C.

100 g of steamed solid A was subjected to a contact with 109.1 g of 85wt % H₃PO4 in 320 ml H₂O under reflux condition for 4 h. Then 100 g ofxonotlite (calcium silicate) were added to the mixture followed bystirring at room temperature for 30 min and evaporation. The sample ishereinafter identified as sample D.

Example 2 Comparative

This example illustrates the fact that the phosphated active phase isnot necessary a good catalyst for conversion of oxygenates. The blendingwith binder and the consequence of the step given in the claims are morethan a simple dilution effect.

25 g of sample B (containing 5 wt % of phosphorous) was additionallydried at 400° C. for 3 h and washed for 2 h at 80° C. with distilledwater followed by filtering at room temperature (P=3.4 wt %, Al=2.7 wt%). The resulted solid was equilibrated by steaming at 600° C. for 2 h.

Catalyst tests were performed on 2 g (35-45 mesh particles) of catalystwith a essentially pure methanol feed, at T_(in)=550° C. and at apressure of 0.5 barg and WHSV=1.61⁻¹, in a fixed-bed, down flowstainless-steel reactor. Prior to catalytic run all catalysts wereheated in flowing N₂ (5 Nl/h) up to the reaction temperature. Analysisof the products has been performed on-line by a gas chromatographequipped with a capillary column. Catalytic performance of catalyst inTable 1 is given on carbon, dry basis and coke free basis.

TABLE 1 MeOH conversion to HC 6.64 C1 6.28 DME as CH2 55.00 CH3OH as CH238.36 Ethylene 0.11 Propylene 0.11 C4 olefins 0.10 C5 olefins 0.02

Example 3 Working Example

320 g of sample B was blended with 400 g of specific binder (P=16.7 wt%, Si=14.5, Mg=0.19, Al=0.018 wt %, K=230 ppm, Na=230 ppm, Ca=20.3 wt%), 165 ml H₂O, 235 ml of low sodium silica sol containing 34 wt % ofSiO₂, and 2-3 wt % extrusion additives. The mixture was agitated for 30min and extruded.

The specific binder was produced by blending of the equivalent mass ofNH₄H₂PO4 and of the xonotlite in aqueous medium at room temperature (1 gof solid/4 ml of water). Afterward the stirring during 60 min thephosphated xonotlite was separated from the liquid by filtering anddried. The dried product was used as the extrusion component.

The extruded solid was dried 24 h at room temperature, then 16 h atelevated temperature followed by washing and steaming at 600° C. for 2h. The sample hereinafter identified as E.

Catalyst tests were performed on 2 g (35-45 mesh particles) of catalystwith a essentially pure methanol feed, at T_(in)=550° C. and at apressure of 0.5 barg and WHSV=1.6 h⁻¹, in a fixed-bed, down flowstainless-steel reactor. Prior to catalytic run all catalysts wereheated in flowing N₂ (5 Nl/h) up to the reaction temperature. Analysisof the products has been performed on-line by a gas chromatographequipped with a capillary column. Catalytic performance of catalyst inTable 1 is given on carbon, dry basis and coke free basis. The resultsare given for the average catalyst performance during 8 hours on-stream.

TABLE 2 WHSV, h⁻¹ 1.6 4 MeOH conversion, % 100 100 Methane 1.6 1.6Paraffins (n + i + CyP) 6.7 5.7 Olefins (n + i + CyO) 85.4 87.5 Dienes(D) 0.5 0.7 Aromatics (A) 7.4 6.1 Ethylene 13.9 10.0 Propylene 41.8 43.4Σ olefins C4-C5 26.4 30.4

Example 4 Comparative, Extrusion, 40 wt % Zeolite in the Catalyst

356 g of the sample A was extruded with 338.7 g of Nyacol (40 wt % SiO2sol), 311.3 g of fumed silica (FK500), 480 ml H₂O and 2-3% of extrusionadditives. The extruded solid was dried 24 h at room temperature, then16 h at 110° C. followed by calcinations at 500° C. for 10 h. The finalsample contained 40 wt % of zeolite and 60 wt % of SiO2 binder. Theextruded sample was subjected to ion exchange with 0.5M NH4Cl underreflux conditions for 18 h followed by washing with water, drying at110° C. for 16 h and calcinations at 450° C. for 6 h. The shaped andexchanged sample was treated with 3.1M H3PO4 under reflux condition for4 h (1 g/4.2 ml) followed by cooling down, filtration and drying at 110°C. for 16 h.

The phosphated sample was washed at room temperature with 0.1M solutionof calcium acetate for 2 h (1 g/4.2 ml). Then the washed sample wasdried at 110° C. for 16 h and steamed in 100 wt % H₂O for 2 h at 600° C.

Example 5 Comparative, Extrusion, 40 wt % Zeolite in the Catalyst

The sample from example 4 was washed one more times at room temperaturewith 0.1M solution of calcium acetate for 2 h (1 g/4.2 ml). Then thewashed sample was dried at 110° C. for 16 h and steamed in 100 wt % H₂Ofor 2 h at 600° C.

The examples 4&5 illustrate the recipe when the sample was firstsubjected in a contact with binder followed by phosphatation.

Example 6 Working, Extrusion, 40 wt % Zeolite in the Catalyst

4 g of the sample B was washed at room temperature with 0.1M solution ofcalcium acetate for 2 h (1 g/4.2 ml), filtered and dried at 110° C. for16 h. The 4 g of dried sample were extruded with 6 g of specific binderand 2-3 wt % of extrusion additives with the zeolite/binder ratio 40/60.The binder was obtained by blending of 40 g of xonotlite with 10 g ofalumina (Condea ˜75 wt % Al₂O₃), 50 g (NH4)H₂PO₄ and 50 ml H₂O at 60° C.followed by filtering and drying at 110° C. for 16 h. The sodium contentin the specific binder was 200 ppm.

The extruded solid was dried at 110° C. for 16 h followed bycalcinations at 600° C. for 10 h.

This example shows a use of pre-phosphated sample for making aformulated catalyst by means of extrusion with a low sodium binder.

Example 7 Working, Spray-Drying

356 g of the sample A was subjected to a contact with 288 g of 85 wt %H3PO4+972 ml H₂O at reflux condition for 4 h. Then the mixture wascooled down to room temperature and 336 g of low sodium alumina sol (20wt % of alumina) was added. The resulted solution was keeping understirring for 30 min followed by slow addition of NH₄OH up to theresulted pH of the solution about 6.5. Then the mixture was left formaturation for at least 1 h followed by addition of 48 g of kaolin and720 g of low sodium silica sol (34 wt % SiO₂, 200 ppm Na). The final pHof the slurry was about ˜6. The resulted slurry was kept under stirringfor at least 30 min and spray-dried. The spray-dried sample was washedwith water, dried and calcined at 700° C. for 2 h.

Example 8 Working, Spray-Drying

150 g of the sample B was subjected to a contact with 630 ml of aqueoussolution containing 1.5 g of dispersed xonotlite followed by addition of450 g of low sodium silica sol (34 wt % SiO₂ in water, 200 ppm Na). Thenthe solution was stirred for one hour and spray-dried. The spray-driedsolid was washed with water at room temperature for 2 h followed byfiltering, drying at 110° C. for 16 h and calcinations at 700° C.

Example 9 Working, Spray-Drying

100 g of the sample C was subjected to a contact with 420 ml of aqueoussolution containing 1 g of dispersed xonotlite followed by addition of300 g of low sodium silica sol (34 wt % SiO₂ in water, 200 ppm Na). Thenthe solution was stirred for one hour and spray-dried. The spray-driedsolid was washed with water at room temperature for 2 h followed byfiltering, drying at 110° C. for 16 h and calcinations at 700° C.

Example 10 Working, Spray-Drying

100 g of the sample D was subjected to a contact with 420 ml of aqueoussolution containing 1 g of dispersed xonotlite followed by addition of150 g of low sodium silica sol (34 wt % SiO₂ in water, 200 ppm Na). Thenthe solution was stirred for one hour and spray-dried. The spray-driedsolid was washed with water at room temperature for 2 h followed byfiltering, drying at 110° C. for 16 h and calcinations at 700° C.

Example 11 Working, Spray-Drying

100 g of the sample A was subjected to a contact with 25 g of 85 wt %H3PO4 at reflux condition for 4 h followed by cooling down and additionof 120 ml of aqueous solution containing 7 g of dispersed xonotlite. Theresulted slurry was kept under stirring for approximately 1 h followedby addition of 300 g of low sodium silica sol (34 wt % SiO₂ in water,200 ppm Na). Then the solution was stirred for one hour and spray-dried.The spray-dried solid was dried at 200° C. for 16 h and washed withwater at room temperature for 2 h followed by filtering, drying andcalcinations at 700° C. for 2 h.

Example 12 MTO Performance

Catalyst tests were performed on 2 g (35-45 mesh particles) of catalystwith a essentially pure methanol feed, at T_(in)=550° C. and at apressure of 0.5 barg and WHSV=1.61⁻¹, in a fixed-bed, down flowstainless-steel reactor. Prior to catalytic run all catalysts wereheated in flowing N₂ (5 Nl/h) up to the reaction temperature. Analysisof the products has been performed on-line by a gas chromatographequipped with a capillary column. Catalytic performance of catalyst inTable 1 is given on carbon, dry basis and coke free basis. The resultsare given for the is average catalyst performance during first 4 hourson-stream.

TABLE 3 Example 4 5 6 7 8 9 10 11 Comp Invention MeOH conv, % 98 100 100100 100 100 100 100 Paraffins 8.8 12.7 6.5 6.2 8.2 7.6 6.8 8.2 Aromatics10.7 12.9 10.5 4.5 6.4 6.5 5.8 8.0 C2═ + C3═ 41.5 49.9 54.7 55.0 54.552.0 51.6 51.3 Ethylene 6.1 20.3 14.6 11.2 14.5 12.4 10.4 12.1 Propylene35.4 29.6 40.1 43.8 40.0 39.6 41.2 39.2

The data illustrate higher yield of propylene obtained on the catalystprepared in accordance with the invention.

1. Use of a catalyst in a MTO process to convert an alcohol or an etherinto light olefins wherein said catalyst comprises a phosphorus modifiedzeolite and is made by a method comprising the following steps in thisorder, a) the essential portion of the phosphorus is introduced into azeolite comprising at least one ten members ring in the structure, b)the phosphorus modified zeolite of step a) is mixed with at least acomponent selected among one or more binders, salts of alkali-earthmetals, salts of rare-earth metals, clays and shaping additives, b)*making a catalyst body from mixture b), c) an optional drying step or anoptional drying step followed by a washing step, d) a calcination step,d*) an optional washing step followed by drying, e) optionally a smallportion of phosphorus is introduced in the course of step b) or b)* orat end of step b) or b)*.
 2. Use according to claim 1 wherein the amountof phosphorous introduced into the zeolite at step a) is from 0.5 to 30wt %.
 3. Use according to claim 2 wherein the amount of phosphorousintroduced into the zeolite at step a) is from 0.5 to 9%.
 4. Useaccording to claim 1 wherein the zeolite (or molecular sieve) containsless that 1000 wppm of sodium, less that 1000 wppm of potassium and lessthat 1000 wppm of iron.
 5. Use according to claim 1 wherein the zeolitecontains less than 100 ppm of red-ox and noble elements such as Zn, Cr,Ti, Rh, Mn, Ni, V, Mo, Co, Cu, Cd, Pt, Pd, Ir, Ru, Re.
 6. Use accordingto claim 1 wherein alkali-earth metals and salts of rare-earth metalsare Ca, Mg, Sr, Ce, La or a combination thereof.
 7. Use according toclaim 1 wherein the zeolite structures are selected from the MFI, MTT,FER, MEL, TON, MWW, EUO, MFS, ZSM-48.
 8. Use according to claim 1wherein the proportion of the P-zeolite is from 15 to 90 w % of thecatalyst.
 9. Use according to claim 1 wherein the concentration of thesalts of alkali-earth metals and salts of rare-earth metals is from 0.1to 15 wt % of the catalyst on metal basis (Me).
 10. Use according toclaim 9 wherein the molar ratio of (Al+Me)/P in the catalyst is in therange 0.5 to 3, where the Me is alkali or rare-earth.